by Neil Nelson
Weather balloons are used in the measurement and evaluation of the upper
atmosphere. Information may be gathered during the ascent of the balloon through
the atmosphere or during its or its motions once it has reached a predetermined
altitude. However, the era of weather ballooning seem ending as other techniques
such as radar, Geostationary satellites and aircraft. The use of balloons
however, still remains widespread.
The balloons are normally filled with helium because of its very low density
and because it is so unreactive.
There are different types of weather balloons -
||Pilot balloons are small fairly small and are used to work
out wind speeds at various altitudes.
||Another small balloon is a ceiling balloon used to
determine the altitude of clouds.
||Much larger are Tear Drop balloons. They often carry a
"Radiosonde" which are radio-transmitting instruments. "Radiosondes"
are a major source of weather information. They typically carry aloft a
compact combination of temperature, pressure, and humidity sensors. The
tear drop balloon expands as it rises as the atmospheric pressure drops.
They typically rise to 90000 feet (28000m) before it bursts. A cute
parachute lowers the instruments to the ground. Such balloons are also
used for horizontal sounding of the atmosphere.
Nowadays, many balloons are monitored from space by satellites.
||Tetroons are tetrahedral balloons used for horizontal
sounding and are designed to withstand extremely low pressures (without
bursting like Tear Drops). They are used extensively in tracing
low-level atmospheric currents by following their movements using radar;
they are therefore increased the meteorologists understanding of
turbulence, low level vertical motions and air pollution.